1. Field of the Invention
This invention relates to a new and improved container closure and container neck structure and more particularly to a structure wherein the closure is applied with a single one-dimensional axial downward force onto the neck and is held in such position by a tamper-evident band. The consumer destroys a frangible connection between the cap and the band during initial removal, preferably by tearing away the band enabling the closure to be unscrewed from the container neck. When the cap is used for reclosure purposes, it may be screwed on and screwed off in the same manner as screw caps have heretofore been used.
2. Description of Related Art
Prior snap-on, screw-off structures may be classified under either of the following categories:
(1) Those with thread engagement as initially applied, PA2 (2) Those without.
The major advantages of the no-thread initial engagement systems are that they are conceptually simple, careful alignment of the closure and the container is not necessary upon application of the closure, and easy (low force) application is possible since no thread-jumping is required. This version can be an aesthetically pleasing, straight wall of threads. On the other hand, the disadvantages of such a system are that it may be confusing to the consumer because initial removal is merely by lifting the cap off the neck but subsequent use requires twisting the cap relative to the neck. Further, it is difficult to use the system with a lined closure because of the height relationships between the finish and the cap, and finally the cap must be relatively tall, which forces the use of fine threads, which can be difficult to mold. None of these disadvantages are present in this invention.
A closure such as Cresci U.S. Pat. No. 4,561,553 has a number of problems. The tamper evident feature of the closure may be circumvented by being able to engage the threads of the neck and closure (thereby creating a mechanical advantage) and back off the cap while the tamper-evident band is intact. Secondly, the device is confusing to the consumer since the cap is screwed off during removal only by inwardly distorting the cap skirt. The cap is reapplied as a standard snap cap. thread engagement as the cap is initially applied has a number of conceptual advantages. Consumer confusion is eliminated since initial removal is by unscrewing. A number of seal systems, including foil, full liner, plugs or other linerless seals can be used. However, full engagement systems heretofore have been difficult to achieve in practice. A disadvantage of a closure such as Carr U.S. Pat. No. 4,625,875 is that there is no practical, consistent means to orient the cap relative to the container so that, after application, the cap must be turned at least slightly to ensure a tight seal. This defeats the purpose of a push-on cap. Also, the use of a stretch snap-band tamper evident ring excessively increases the application force necessary to seat the cap.
The present invention provides full thread engagement by reason of unique thread design and, more particularly, a unique tamper-evident band (i.e., lower skirt portion) attached to the upper part of the cap by multiple bridges or by means of a continuous line of weakness between the cap and tear band, as well as a means of orienting closure and bottle threads to achieve registration prior to straight axial application.
The present invention has considerable advantages over prior structures for the reasons above noted, among others.